The invention relates to a measurement device for determining the oxygen activity in molten metal or slag with a measurement head, which is arranged at one end of a carrier tube and on which an electrochemical measurement cell is arranged. The electrochemical measurement cell has a solid electrolyte tube, which is closed on one end and which contains a reference material and an electrode at its closed end, wherein the electrode projects out of the opposite end of the solid electrolyte tube. In addition, the invention relates to a solid electrolyte tube for an electrochemical measurement cell.
Such measurement devices are known, for example, from German Patent DE 31 52 318 C2. The sensor described in this document is used to measure the concentration of oxygen in molten metal. Similar measurement devices are also known from U.S. Pat. No. 3,578,578, German published patent application DE 28 10 134 A1, or German Patent DE 26 00 103 C2.